A loss of muscle mass in dog legs along with other physical and behavioral changes are associated with old age. You may have noticed that your dog's thighs are thin, have decreased muscle tone and are weak. The old adage "use or lose it" is applicable as well to when it comes to a dog's muscles. The less the muscles are used, the more those muscle will start losing mass. If you are noticing a loss of muscle mass in dog legs, you may be wondering what it is causing it in the first place and what you can do to prevent your dog from losing further muscle mass.
Atrophy, Loss of Muscle Mass in Dog Legs
The medical term for loss of muscle mass in dogs legs is muscle atrophy, which depicts the gradual wasting seen in a dog's muscles. The muscle wasting observed may affect one limb or it can affect more than one limb. Often the loss of muscle is seen in the hind legs, but it can occur in the front legs as well.
It's important to recognize that loss of muscle mass in dog legs should be taken seriously and addressed by a vet. Why does this matter?
Atrophy of the dog's muscles is a debilitating condition because when the muscles atrophy, dogs develop weakness, which is especially seen in their hind quarters. This may rob them from the basic strength necessary for walking as they are meant to, which, as one can imagine, will only lead to further loss of muscle mass and its associated loss of functionality.
This vicious cycle of loss of functionality needs to be interrupted to restore dogs back to better health and mobility. It's therefore important to see the vet so to address the underlying cause considering that muscle atrophy in dogs tends to occur secondary to other conditions.
A Matter of Disuse
"Use it or lose it" is the perfect saying to depict the loss of muscle mass in dogs seen in what is called "disuse athrophy." In disuse atrophy, as the name implies, the muscles starts losing mass because they are no longer exercised. Now here's the catch...
Muscles need constant activity in order to keep their mass, so the less they are used, the smaller they get. This type of muscle wasting in dogs usually occurs secondary to painful conditions such as arthritis, which leads to dogs shifting their weight more on their front and moving around less. In a case as such, the loss of muscle mass is usually symmetrical (affecting both sides) and tends to occur over the course of weeks to months, observes veterinarian Dr. Gene.
In this case of muscle wasting, it's therefore important to pinpoint the underlying cause of pain. Thigh muscle atrophy in dogs can be due to hip dysplasia, a torn cruciate ligament or even bone cancer.
A Matter of Nerves
The other type of atrophy affecting dogs is the neurogenic type, which, as the name implies, originates from the dog's nervous system. What happens here is that the activity of the nerves that supply the dog's legs is interrupted. With less innervation, the dog's muscle tone decreases and the muscles become smaller and weaker.
This type of loss of muscle mass in dog legs is therefore secondary to conditions causing destruction of nervous tissue such as herniated discs compressing the dog's spinal cord. In a case as such, the loss of muscle mass is rapid (over days or weeks) and is often associated with lack of motor function. Affected dogs may drag their toes, scuffing the top surface of their paw as they walk and their nails may consume unevenly.
A condition to keep in mind in dogs losing muscle mass and developing weakness in their hind legs is degenerative myelopathy (DM). This condition is more prevalent in older German shepherds, but it can affect other breeds of dogs. Affected dogs develop progressive weakness in their back legs along with a wobbly, drunk-like gait. Muscle disease (myositis) is something to consider as a possible cause.
At the Vet's Office
If your dog is experiencing muscle wasting with its associated atrophy, your vet will perform a throughout examination. If your dog is lame, your vet may take a look at your dog's gait both walking and trotting. He may palpate the legs and spine to look for signs of stiffness and pain.
A neurological examination may involve your vet testing your dog's ability to re-position his paws after turning them over (proprioception).
Blood tests may help asses overall health and rule out leg pain due to tick-born disease. X-rays of the dog's legs and spine may be ordered to look for proof of degeneration, but several signs of nerve problems tend to not show up on x-rays. An MRI or CT scan may be needed to rule out or confirm intervertebral disc disease.
Treatment for loss of muscle mass in dog legs is based on the veterinarian's findings. If the affected dog is not using his legs as before due to chronic painful conditions such as arthritis from wear and tear or an old ruptured cranial cruciate ligament, the vet may prescribe pain medication, muscle relaxants and anti-inflammatory drugs.
To help dogs suffering from loss of muscle tone, there are several options to gain back some mass. Your vet may recommend rehabilitation services such as massage, passive range of motion exercises and the use of underwater treadmills. Water helps build muscles in a low impact way that is advantageous to dogs with loss of muscle mass. Acupuncture and supplements may further provide additional help.
- L. Mahin - Own work Muscular atrophy of thigh of a crossed shepherd dog with two-year-old hip dispasia CC BY-SA 3.0